Biomimetic epoxidation of alkenes with sodium periodate catalyzed by tetraphenylporphyrinatomanganese(III) chloride supported on multiwall carbon nanotubes Maryam Zakeri • Majid Moghadam • Iraj Mohammadpoor-Baltork • Shahram Tangestaninejad • Valiollah Mirkhani • Ahmad Reza Khosropour • Mohammad Alizadeh Received: 10 August 2011 / Accepted: 17 October 2011 / Published online: 8 November 2011 Ó Springer Science+Business Media B.V. 2011 Abstract The biomimetic epoxidation of alkenes cata- lyzed by tetraphenylporphyrinatomanganese(III) chloride, [Mn(TPP)Cl], immobilized on multiwall carbon nanotubes modified with 4-aminopyridine and 4-aminophenol is reported. These heterogenized catalysts were used as effi- cient and reusable catalysts for epoxidation of a variety of cyclic and linear alkenes with sodium periodate under mild conditions. The catalysts, [Mn(TPP)Cl@amine-MWCNT], were characterized by physico-chemical and spectroscopic methods. The effect of ultrasonic irradiation on these cat- alytic systems was also investigated. The catalysts were reused several times without loss of their activity. Introduction Catalytic oxidation of hydrocarbons in organic liquid phase by oxo metalloporphyrins, in which the metal possesses high oxidation number, has attracted much attention by mimicking the function of monooxygenase enzymes like cytochrome P-450. In the presence of single oxygen donors such as iodosylbenzene [1, 2], hypochlorites [3, 4], amine N-oxides [5], alkyl hydroperoxides [6], hydrogen peroxide [7, 8] and sodium periodate [9, 10], natural cytochrome P-450 and metalloporphyrin complexes are able to oxidize organic compounds. Homogenous metalloporphyrins readily undergo decomposition during the oxidation reaction, which leads to the formation of l-oxo catalytically inactive dimers in solvent. Hence, immobilizing these expensive catalysts on to a solid organic or inorganic support can overcome this problem [11, 12]. Although the reactivity of this heterog- enized catalyst is often lower than the homogenized counterpart, recovery and reusability of the catalyst makes it cost-effective. Manganese porphyrins can be immobilized on variety of supports via different methods, including coordination bonding, covalent anchorage, electrostatic interactions, encapsulation and intercalation. In the last two decades, several manganese porphyrins have been successfully attached to different supports and investigated for catalytic activity in organic reactions. Previously, our research group reported the catalytic activity of manganese por- phyrins immobilized on silica, polystyrene, ion-exchange resins and zeolite. Recently, we reported the preparation of tetrakis(p-aminophenyl)porphyrinatomanganese(III) chlo- ride, [Mn(TNH 2 PP)Cl], supported on multiwall carbon nanotubes via covalent attachment. All of them were used for alkene epoxidation with NaIO 4 [9, 10, 13–22]. Carbon nanotubes (CNTs) offer an ideal opportunity as a support because of their large specific surface area, water insolubility and chemical inertness. These long tubes have attracted a lot of attention from researchers around the world [23–25]. The use of ultrasound to improve the catalytic activity of metalloporphyrins has been reported [26–30]. The ability of ultrasound to create highly reactive surfaces and to increase mass transfer makes it a particularly elegant technique for activation of the catalyst. The main effect of Electronic supplementary material The online version of this article (doi:10.1007/s11243-011-9555-2) contains supplementary material, which is available to authorized users. M. Zakeri Á M. Moghadam (&) Á I. Mohammadpoor-Baltork Á S. Tangestaninejad Á V. Mirkhani Á A. R. Khosropour Á M. Alizadeh Department of Chemistry, Catalysis Division, University of Isfahan, Isfahan 81746-73441, Iran e-mail: moghadamm@sci.ui.ac.ir 123 Transition Met Chem (2012) 37:45–53 DOI 10.1007/s11243-011-9555-2